The invention relates to an intake system for an internal-combustion engine having a suction manifold which comprises a chamber and which, on the inflow side, has an intake connection and, on the outflow side, has several individual suction pipes which lead into a cylinder head of the internal-combustion engine and are connected with the individual cylinders.
Because of a variable rate of air flow to the individual cylinders of the internal-combustion engine, airborne noises occur in an intake system which are transmitted to the outside by way of the chamber of the system and represent a deterioration of comfort.
It is an object of the invention to provide an intake system for an internal-combustion engine which causes a reduction of the airborne noises.
According to the invention, this object is achieved by providing an intake system of the above-noted type, characterized in that the intake connection has an air guiding device which extends approximately to a plane which extends between the two center suction pipes enclosed by the outer suction pipes and in the axial direction of the individual suction pipes and a wall of the air guiding device directed toward the interior openings of the suction pipes is arranged at a distance from these openings.
For reducing airborne noises, an air guiding device is arranged in the chamber of the intake system which is connected or arranged with the intake connection. As a result, the taken-in air is guided in a forced manner in the area of the two first cylinder intake pipes. The device may be constructed in one piece with the chamber, in which case an interior wall will then extend at a distance from the inlet openings of the suction pipes.
Additional embodiments contain inserted pipes which are connected with the pipe socket of the chamber by way of special fastening devices and project into it in an open manner.
The pipe consists of a plastic material and is subjected to thermal stress because of the relatively high wall temperature of the chamber of approximately 150.degree. C. which causes the plastic material to soften and the hold in the intake connection ms therefore reduced.
During the cooling of the internal-combustion engine after the stoppage, the softened plastic material of the pipe wall will harden again. In the case of numerous softening and hardening processes of the pipe, which corresponds to a normal operation of the internal-combustion engine, as well as in the case of high vibration stress to which the components are subjected during the engine operation, a gap is formed at the connecting point between the pipe and the chamber which may lead to the destruction of the pipe.
In order to avoid this disadvantage, an annular groove is provided in the pipe into which a spring ring is inserted. In the area of the spring ring, the pipe wall has a thickening so that, when the pipe is heated, the spring groove can radially expand without any loss of stability and takes up a position in which it rests against a corresponding annular slot, and a secure fastening is therefore ensured.
According to the other embodiments, in addition to the axial securing, a rotational securing is also provided between the intake connection and the pipe. This rotational securing consists essentially of a raised pressed-out portion which extends in the axial direction of the pipe and which engages in a corresponding pressed-out portion of the connection.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.